waiting for a cancellation; being on standby; being on a waiting list
Colloquial abbreviation of キャンセル待ち. Used when someone is on a waiting list hoping for a cancellation, e.g., for a reservation, ticket, or appointment.
See also: キャンセル待ち
I finally got into the popular restaurant by waiting for a cancellation.
I'm on standby for the flight, but I don't know if a seat will open up.
A shortening of キャンセル待ち “waiting for a cancellation,” with キャン clipped from the English loanword キャンセル.